This invention relates to a tool capable of finishing the periphery of an object.
Many machines in the current art are designed to rotate an abrasive belt or wire brush about a fixed axis at a relatively low speed while driving the tool about its own axis at a much higher speed. Such a tool will present the outside surface of an object centered around the fixed axis to a rapidly moving finishing surface which evenly covers all points on the object's periphery.
An early version of such a machine described in U.S. Pat. No. 799,422, issued to Bornman, includes a pair of abrading belts which are bolted in place prior to operation. The Bornman tool employs a feed unit to allow continuous sanding operations, but changes in abrading pressure while the machine is running are not possible.
U.S. Pat. No. 1,215,482, issued to Chamberlain, describes a cleaning machine employing a pair of rotating brushes. The Chamberlain machine may be operated in one mode to clean flat stock, wherein the cleaning brushes rotate about their own axis in a stationary orbital position, or in a second mode in which the brushes orbit about the axis of a round stock. In either mode, however, the brushes must be present prior to operation.
The problem of providing on operation adjustment of abrading pressure is met to some extent by U.S. Pat. No. 3,071,903, issued to Wing, et al. In the Wing device two continuous belts are moved toward the workpiece by flyweights as the orbital velocity of the belts is increased. Belt pressure is, however, a function of the orbital velocity, and cannot be regulated unless a variable speed motor is used.
Still another machine in the present art, described in U.S. Pat. No. 3,526,060, issued to Hall, et al, provides a threaded shaft for adjustment to accommodate various sized workpieces without altering the orbital velocity of the abrader. Again, however, on operation adjustment is not possible.
It would be of considerable advantage, therefore to provide an orbital abrader in which the orbital radius can be varied during the abrading operation. Such a machine would allow adjustments for variations among objects to be operated on by the abrader without the necessity of stopping the machine for each such adjustment. Various abrading operations, such as sanding oversized tube ends for correct fit in joints to be brazed, finishing the tube ends prior to assembly cryogenic fittings to eliminate minor extrusion scratch paths, deburring tubing, shaping, etc., would be greatly expedited by such a machine.